This issue reiterates QTBUG-114115 (Unable to run on Gitlab CI / Windows Server Core docker image - Qt Bug Tracker), which is still an issue (in a similar way) on 6.5.3. This time, the error reported related to missing Windows.UI.ViewManagement.dll/Windows.UI.dll/Windows.dll. 

I hope this is a QTBUG rather than a PYSIDE issue, but I am happy to refile as such if it is.

There is extensive debug logs at build (#5230499449) - Jobs - bers / pyside-issues - GitLab vs build (#5230481724) - Jobs - bers / pyside-issues - GitLab, with the only difference between the two being the PySide6 version (6.4.3 vs. 6.5.3). Pipeline configs for these runs are at .gitlab-ci.yml - 16cb0c631d0bbb8cea60b9e050f690954969a3e7 - bers / pyside-issues - GitLab and .gitlab-ci.yml - 0008c6ba6b2cd2c683f8ec5f62c6c5690048f185 - bers / pyside-issues - GitLab, respectively.

On my Windows 10 system, procmon reports Windows.UI.dll being loaded, so this one seems to be required.

To explain the seriousness of this, which maybe I failed to bring across previously: for me, this issue means that GitLab CI cannot be used to pytest applications (or pyinstaller bundles) which use QApplication in PySide6 6.5. (IIRC, not even linting works, although I am not sure about this right now.) All this works flawlessly in 6.4.3, and losing this functionality in 6.5 is a big deal to me. In particular, since this has been going on since 6.5.0, this issues has been existing for 6 months now. At the same time, I need to use 6.5.0 due to PYSIDE-2141, so I am essentially stuck at not having CI at all.

If there is a workaround using environment variables or whatever else for QApplication() not to required said dll files, I would be more than happy.